title: Evolvability of thermophilic proteins from archaea and bacteria.
abstract: Proteins from thermophiles possess high thermostability. The stabilization mechanisms differ between archaeal and bacterial proteins, whereby archaeal proteins are mainly stabilized via hydrophobic interactions and bacterial proteins by ion pairs. High stability is an important factor in promoting protein evolution, but the precise means by which different stabilization mechanisms affect the evolution process remain unclear. In this study, we investigated a random mutational drift of esterases from thermophilic archaea and bacteria at high temperatures. Our results indicate that mutations in archaeal proteins lead to improved function with no loss of stability, while mutant bacterial proteins are largely destabilized with decreased activity at high temperatures. On the basis of these findings, we suggest that archaeal proteins possess higher "evolvability" than bacterial proteins under temperature selection and are additionally able to evolve into eukaryotic proteins.
authors.affiliation: Department of Biomolecular Chemistry, Kyoto Prefectural University , 1-5 Hangi-cho, Shimogamo, Sakyo-ku, Kyoto 606-8522, Japan.
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Takano
authors.forename: Atsushi
authors.initials: A
authors.lastname: Aoi
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Koga
authors.forename: Shigenori
authors.initials: S
authors.lastname: Kanaya
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D019020:Directed Molecular Evolution; D008958:Models, Molecular; D016133:Polymerase Chain Reaction; D013696:Temperature
chemical_list: D019843:Archaeal Proteins; D001426:Bacterial Proteins